Titanium base alloys containing chromium and carbon



Patented Aug. 24, 1954 TITANIUM BASE ALLOYS CONTAINING CHROMIUM AND CARBON Charles M. Graighead, Columbus, Ohio, assignor,

by meme assignments, to The Battelle Develop-- ment Corporation, Columbus, Ohio, at corporation of Delaware No Drawing. Application October 6-, 1950, Serial No. 188,891

2 Claims. 1'

This invention relates to titanium-base alloys and, more particularly, to titanium-base alloys containing chromium and carbon, and is a continuation-impart of co-pending application, Serial No. 36,434, filed July 1, 1948, now abandoned.

It has become generally recognized that titanium metal possesses valuable properties which render it desirable for various structural uses and for other purposes. For example, the metal has an excellent strength/Weight ratio, good corrosion properties, and is useful for high-temperature applications. However, these various properties of titanium are not ordinarily subject to adjustment to meet specific requirements imposed by particular applications. For this reason then, as well as for purposes of improving the properties of the base metal, it is desirable to produce alloys of titanium which will possess desired properties in the required degree, or which will respond to heat treatment, or other methods for enhancing a particular quality (characteristic) or property.

It is accordingly an object of this invention to provide alloys of titanium containing chromium and carbon.

It is another object of this invention to provide titanium-chromium-carbon alloys having desirable properties for structural or other purposes.

Yet another object of this invention i to produce titanium-chromium-carbon alloys which are responsive to heat treatment.

Other objects and advantages of the present invention will be apparent in view of the following detailed description thereof.

In general, this invention relates to alloys of titanium containing chromium and carbon. In particular, the invention relates to titanium alloys containing from about 1.5% to about 7.5% chromium and from about 0.2% to about 0.6% carbon. A preferred range of from 2.5% to 5.0% chromium and 0.25% to 0.5% carbon has also been established.

Titanium-chromium-carbon alloys may be prepared in accordance with present-day melting techniques which form no part of the present invention and need not be discussed further here.

Table I below lists typical values obtained in physical tests of titanium-chromium-carbon alloys. Properties listed are the as-hot-roli'ed values (at 1450 F.).

Table I Composition 1 Elonga- Tensile Intended Actual i Swing. g t H. N

i p men in l-in. Percent Percent Percent Cr. Or

2. 5 0. 25 2. 25 141, 400 7. 5 305 2. 5 0. 25 2. 28 171, 200 8. 0 336 3. 5 (l. 25 3. 23 160, 200 5. O 262 5. 0 0. 25 4. 94 179, 900 5. 0 349 5. 0 0. 25 4. 27 158, 100 6. 5 288 10. 0 0. 25 9. 40 179, 400 3. 5 383 15. 0 0. 25 14. 40 171, 000 6. 0 34B 2. 5 0. 2.15 128, 200 ll. 5 245 3. 5 D. 50 3. 35 146, 900 7. 0 266 5. 0 0. 50 4. 21 155, 300 5. 0 280 1 Balance Ti.

3 No analysis made for O.

From the table above, it will be apparent that titanium-chromium-carbon alloys in the preferred range possess good tensile properties combined with sufiicient ductility to permit ordinary working of the alloys. Furthermore, alloys in the range 1.5% to 7.5% chromium, 0.2% to 0.6% carbon, the balance essentially all titanium, possess these properties, although to a slightly lesser degree. These alloys also have the corrosion resistance and other desirable properties ordinarily imputed to titanium and titanium alloys.

That the alloys of the present invention respond to heat treatment is indicated by the data in Table II, wherein it will be noted that the hardness is generally increased by heat treatment at temperatures in the range 1450" F. to 1750 F., and also by aging at 750 F. for various periods of time ranging from two to twelve hours. The particular heat treatment which eiiected the hardness changes reported consisted of heating specimens in air for 30 minutes at the designated temperature and then quenching in cold water. Each value reported represents the average of at least five readings taken at the center of a cross-section perpendicular to the direction of rolling.

Table II Composition Vickers Hardness Number Altar Heat V. H. N. as Hot-Rolled and Aged V H N Treatment Atat 750 F. for-- Intended Actual Amiga? Rolled Pement Percent Percent Percent 1,450 1,550" 1,600 1,650 1,7D 1,750 0 2 4 8 12 0t 0 Or 0 F. F. F. F. F. F. Hours Hours Hours Hours Hours 2. 0. 25 2. 25 305 301 318 314 327 339 369 305 318 2. 5 0. 25 2. 28 0. 28 336 304 307 377 326 354 363 365 327 3. 5 0.25 3. 23 262 312 332 320 321 319 380 262 345 5. 0 0. 25 4. 94 0. 25 349 353 386 392 353 383 387 398 352 5.0 0.25 4. 27 288 310 376 303 309 312 314 288 357 1D. 0 0. 25 9. 40 0. 28 383 443 326 333 376 506 503 482 456 16. 0 0. 25 14. 40 0. 13 346 337 334 i h- 370 317 465 459 488 427 1 Balance titanium.

1 Held at indicated temperature for 30 minutes and quenched in cold water.

It will now be apparent that new and useful of this invention which is hereinafter defined in the claims.

What is claimed is:

1. An alloy consisting essentially of from about 1.5% to about 7.5% chromium, from about 0.2%

to about 0.6% carbon, and the balance titanium,

said alloy being characterized by having a minimum tensile strength of about 128,200 p. s. i. and a minimum elongation of about 5.0% in the ashot-rolled (at 1450 F.) condition.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,471,326 Copland Oct. 23, 1923 OTHER REFERENCES Zeitschrift fur Metallkunde, vol. 29 (1937), page 190.

Metal Progress, March 1949, page 348.

"Metal Progress," November 1949, page 658.

Product Engineering," November 1949, page 148.

"Industrial and Engineering Chemistry, Feb- Z. An. 8.110) consisting 0f flOIl'l about 2.5% t0 ruary 1950 pages 222 22 243 about 5.0% chromium, from about 0.25% to about 0.50% carbon, and the balance titanium. 

2. AN ALLOY CONSISTING OF FROM ABOUT 2.5% TO ABOUT 5.0% CHROMIUM, FROM ABOUT 0.25% TO ABOUT 0.50% CARBON, AND THE BALANCE TITANIUM. 